(a) Field of the Invention
The present invention relates to a temperature control apparatus of a fixer in a recording apparatus such as a copying machine or a laser beam printer.
(b) Description of the Prior Art
In a conventional fixer of a recording apparatus of this type, the temperature of the fixer is detected by a heat-sensitive element such as a thermistor, and ON/OFF control of a heating source such as a heater is performed in accordance with a predetermined reference temperature. More specifically, assume that the predetermined reference temperature is set at 180.degree. C. Then, if the detected temperature is lower than the reference temperature, the heater is turned on. On the other hand, if the detected temperature is higher than the reference temperature, the heater is turned off.
In a fixer of this configuration, there is some waiting time after power is turned on before the fixer reaches a predetermined temperature and a recording operation can be performed. In order to shorten this waiting time, it has been proposed to use a heater of higher output power. However, if the output power of the heater is too high, the fixer may be damaged by overshoot or the like after being kept ON until the reference temperature is reached.
Moreover, when such a high output heater is used, a rush current flows to the heater when the heater is turned on. This results in an input power down; a steady state can only be attained after a considerable length of time. This may also adversely affect AC loads.